/*
 * Copyright (c) 2009-2010, Salvatore Sanfilippo <antirez at gmail dot com>
 * Copyright (c) 2010, Pieter Noordhuis <pcnoordhuis at gmail dot com>
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <string.h>
#include <stdlib.h>
#ifndef _WIN32
#include <unistd.h>
#endif
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <ctype.h>

#include "hiredis.h"
#include "net.h"
#include "sds.h"
#include "util.h"

#ifdef _WIN32
#include <winsock2.h>
#endif

#ifdef _WIN32
#define va_copy(d,s) d = (s)
#endif

typedef struct redisReader {
	struct redisReplyObjectFunctions *fn;
	sds error; /* holds optional error */
	void *reply; /* holds temporary reply */

	sds buf; /* read buffer */
	size_t pos; /* buffer cursor */
	size_t len; /* buffer length */

	redisReadTask rstack[9]; /* stack of read tasks */
	int ridx; /* index of stack */
	void *privdata; /* user-settable arbitrary field */
} redisReader;

static redisReply *createReplyObject(int type);
static void *createStringObject(const redisReadTask *task, char *str, size_t len);
static void *createArrayObject(const redisReadTask *task, int elements);
static void *createIntegerObject(const redisReadTask *task, long long value);
static void *createNilObject(const redisReadTask *task);
static void redisSetReplyReaderError(redisReader *r, sds err);

/* Default set of functions to build the reply. */
static redisReplyObjectFunctions defaultFunctions = {
	createStringObject,
	createArrayObject,
	createIntegerObject,
	createNilObject,
	freeReplyObject
};

/* Create a reply object */
static redisReply *createReplyObject(int type) {
	redisReply *r = malloc(sizeof(*r));

	if (!r) redisOOM();
	r->type = type;
	return r;
}

/* Free a reply object */
void freeReplyObject(void *reply) {
	redisReply *r = reply;
	size_t j;

	switch (r->type) {
	case REDIS_REPLY_INTEGER:
		break; /* Nothing to free */
	case REDIS_REPLY_ARRAY:
		for (j = 0; j < r->elements; j++)
			if (r->element[j]) freeReplyObject(r->element[j]);
		free(r->element);
		break;
	case REDIS_REPLY_ERROR:
	case REDIS_REPLY_STATUS:
	case REDIS_REPLY_STRING:
		free(r->str);
		break;
	}
	free(r);
}

static void *createStringObject(const redisReadTask *task, char *str, size_t len) {
	redisReply *r = createReplyObject(task->type);
	char *value = malloc(len + 1);
	if (!value) redisOOM();
	assert(task->type == REDIS_REPLY_ERROR ||
		task->type == REDIS_REPLY_STATUS ||
		task->type == REDIS_REPLY_STRING);

	/* Copy string value */
	memcpy(value, str, len);
	value[len] = '\0';
	r->str = value;
	r->len = len;

	if (task->parent) {
		redisReply *parent = task->parent->obj;
		assert(parent->type == REDIS_REPLY_ARRAY);
		parent->element[task->idx] = r;
	}
	return r;
}

static void *createArrayObject(const redisReadTask *task, int elements) {
	redisReply *r = createReplyObject(REDIS_REPLY_ARRAY);
	r->elements = elements;
	if ((r->element = calloc(sizeof(redisReply*), elements)) == NULL)
		redisOOM();
	if (task->parent) {
		redisReply *parent = task->parent->obj;
		assert(parent->type == REDIS_REPLY_ARRAY);
		parent->element[task->idx] = r;
	}
	return r;
}

static void *createIntegerObject(const redisReadTask *task, long long value) {
	redisReply *r = createReplyObject(REDIS_REPLY_INTEGER);
	r->integer = value;
	if (task->parent) {
		redisReply *parent = task->parent->obj;
		assert(parent->type == REDIS_REPLY_ARRAY);
		parent->element[task->idx] = r;
	}
	return r;
}

static void *createNilObject(const redisReadTask *task) {
	redisReply *r = createReplyObject(REDIS_REPLY_NIL);
	if (task->parent) {
		redisReply *parent = task->parent->obj;
		assert(parent->type == REDIS_REPLY_ARRAY);
		parent->element[task->idx] = r;
	}
	return r;
}

static char *readBytes(redisReader *r, unsigned int bytes) {
	char *p;
	if (r->len - r->pos >= bytes) {
		p = r->buf + r->pos;
		r->pos += bytes;
		return p;
	}
	return NULL;
}

/* Find pointer to \r\n. */
static char *seekNewline(char *s, size_t len) {
	int pos = 0;
	int _len = len - 1;

	/* Position should be < len-1 because the character at "pos" should be
	 * followed by a \n. Note that strchr cannot be used because it doesn't
	 * allow to search a limited length and the buffer that is being searched
	 * might not have a trailing NULL character. */
	while (pos < _len) {
		while (pos < _len && s[pos] != '\r') pos++;
		if (s[pos] != '\r') {
			/* Not found. */
			return NULL;
		}
		else {
			if (s[pos + 1] == '\n') {
				/* Found. */
				return s + pos;
			}
			else {
				/* Continue searching. */
				pos++;
			}
		}
	}
	return NULL;
}

/* Read a long long value starting at *s, under the assumption that it will be
 * terminated by \r\n. Ambiguously returns -1 for unexpected input. */
static long long readLongLong(char *s) {
	long long v = 0;
	int dec, mult = 1;
	char c;

	if (*s == '-') {
		mult = -1;
		s++;
	}
	else if (*s == '+') {
		mult = 1;
		s++;
	}

	while ((c = *(s++)) != '\r') {
		dec = c - '0';
		if (dec >= 0 && dec < 10) {
			v *= 10;
			v += dec;
		}
		else {
			/* Should not happen... */
			return -1;
		}
	}

	return mult*v;
}

static char *readLine(redisReader *r, int *_len) {
	char *p, *s;
	int len;

	p = r->buf + r->pos;
	s = seekNewline(p, (r->len - r->pos));
	if (s != NULL) {
		len = s - (r->buf + r->pos);
		r->pos += len + 2; /* skip \r\n */
		if (_len) *_len = len;
		return p;
	}
	return NULL;
}

static void moveToNextTask(redisReader *r) {
	redisReadTask *cur, *prv;
	while (r->ridx >= 0) {
		/* Return a.s.a.p. when the stack is now empty. */
		if (r->ridx == 0) {
			r->ridx--;
			return;
		}

		cur = &(r->rstack[r->ridx]);
		prv = &(r->rstack[r->ridx - 1]);
		assert(prv->type == REDIS_REPLY_ARRAY);
		if (cur->idx == prv->elements - 1) {
			r->ridx--;
		}
		else {
			/* Reset the type because the next item can be anything */
			assert(cur->idx < prv->elements);
			cur->type = -1;
			cur->elements = -1;
			cur->idx++;
			return;
		}
	}
}

static int processLineItem(redisReader *r) {
	redisReadTask *cur = &(r->rstack[r->ridx]);
	void *obj;
	char *p;
	int len;

	if ((p = readLine(r, &len)) != NULL) {
		if (cur->type == REDIS_REPLY_INTEGER) {
			if (r->fn && r->fn->createInteger)
				obj = r->fn->createInteger(cur, readLongLong(p));
			else
				obj = (void*)REDIS_REPLY_INTEGER;
		}
		else {
			/* Type will be error or status. */
			if (r->fn && r->fn->createString)
				obj = r->fn->createString(cur, p, len);
			else
				obj = (void*)(size_t)(cur->type);
		}

		/* Set reply if this is the root object. */
		if (r->ridx == 0) r->reply = obj;
		moveToNextTask(r);
		return 0;
	}
	return -1;
}

static int processBulkItem(redisReader *r) {
	redisReadTask *cur = &(r->rstack[r->ridx]);
	void *obj = NULL;
	char *p, *s;
	long len;
	unsigned long bytelen;
	int success = 0;

	p = r->buf + r->pos;
	s = seekNewline(p, r->len - r->pos);
	if (s != NULL) {
		p = r->buf + r->pos;
		bytelen = s - (r->buf + r->pos) + 2; /* include \r\n */
		len = readLongLong(p);

		if (len < 0) {
			/* The nil object can always be created. */
			if (r->fn && r->fn->createNil)
				obj = r->fn->createNil(cur);
			else
				obj = (void*)REDIS_REPLY_NIL;
			success = 1;
		}
		else {
			/* Only continue when the buffer contains the entire bulk item. */
			bytelen += len + 2; /* include \r\n */
			if (r->pos + bytelen <= r->len) {
				if (r->fn && r->fn->createString)
					obj = r->fn->createString(cur, s + 2, len);
				else
					obj = (void*)REDIS_REPLY_STRING;
				success = 1;
			}
		}

		/* Proceed when obj was created. */
		if (success) {
			r->pos += bytelen;

			/* Set reply if this is the root object. */
			if (r->ridx == 0) r->reply = obj;
			moveToNextTask(r);
			return 0;
		}
	}
	return -1;
}

static int processMultiBulkItem(redisReader *r) {
	redisReadTask *cur = &(r->rstack[r->ridx]);
	void *obj;
	char *p;
	long elements;
	int root = 0;

	/* Set error for nested multi bulks with depth > 1 */
	if (r->ridx == 8) {
		redisSetReplyReaderError(r, sdscatprintf(sdsempty(),
			"No support for nested multi bulk replies with depth > 7"));
		return -1;
	}

	if ((p = readLine(r, NULL)) != NULL) {
		elements = readLongLong(p);
		root = (r->ridx == 0);

		if (elements == -1) {
			if (r->fn && r->fn->createNil)
				obj = r->fn->createNil(cur);
			else
				obj = (void*)REDIS_REPLY_NIL;
			moveToNextTask(r);
		}
		else {
			if (r->fn && r->fn->createArray)
				obj = r->fn->createArray(cur, elements);
			else
				obj = (void*)REDIS_REPLY_ARRAY;

			/* Modify task stack when there are more than 0 elements. */
			if (elements > 0) {
				cur->elements = elements;
				cur->obj = obj;
				r->ridx++;
				r->rstack[r->ridx].type = -1;
				r->rstack[r->ridx].elements = -1;
				r->rstack[r->ridx].idx = 0;
				r->rstack[r->ridx].obj = NULL;
				r->rstack[r->ridx].parent = cur;
				r->rstack[r->ridx].privdata = r->privdata;
			}
			else {
				moveToNextTask(r);
			}
		}

		/* Set reply if this is the root object. */
		if (root) r->reply = obj;
		return 0;
	}
	return -1;
}

static int processItem(redisReader *r) {
	redisReadTask *cur = &(r->rstack[r->ridx]);
	char *p;
	sds byte;

	/* check if we need to read type */
	if (cur->type < 0) {
		if ((p = readBytes(r, 1)) != NULL) {
			switch (p[0]) {
			case '-':
				cur->type = REDIS_REPLY_ERROR;
				break;
			case '+':
				cur->type = REDIS_REPLY_STATUS;
				break;
			case ':':
				cur->type = REDIS_REPLY_INTEGER;
				break;
			case '$':
				cur->type = REDIS_REPLY_STRING;
				break;
			case '*':
				cur->type = REDIS_REPLY_ARRAY;
				break;
			default:
				byte = sdscatrepr(sdsempty(), p, 1);
				redisSetReplyReaderError(r, sdscatprintf(sdsempty(),
					"Protocol error, got %s as reply type byte", byte));
				sdsfree(byte);
				return -1;
			}
		}
		else {
			/* could not consume 1 byte */
			return -1;
		}
	}

	/* process typed item */
	switch (cur->type) {
	case REDIS_REPLY_ERROR:
	case REDIS_REPLY_STATUS:
	case REDIS_REPLY_INTEGER:
		return processLineItem(r);
	case REDIS_REPLY_STRING:
		return processBulkItem(r);
	case REDIS_REPLY_ARRAY:
		return processMultiBulkItem(r);
	default:
		assert(NULL);
		return -1;
	}
}

void *redisReplyReaderCreate(void) {
	redisReader *r = calloc(sizeof(redisReader), 1);
	r->error = NULL;
	r->fn = &defaultFunctions;
	r->buf = sdsempty();
	r->ridx = -1;
	return r;
}

/* Set the function set to build the reply. Returns REDIS_OK when there
 * is no temporary object and it can be set, REDIS_ERR otherwise. */
int redisReplyReaderSetReplyObjectFunctions(void *reader, redisReplyObjectFunctions *fn) {
	redisReader *r = reader;
	if (r->reply == NULL) {
		r->fn = fn;
		return REDIS_OK;
	}
	return REDIS_ERR;
}

/* Set the private data field that is used in the read tasks. This argument can
 * be used to curry arbitrary data to the custom reply object functions. */
int redisReplyReaderSetPrivdata(void *reader, void *privdata) {
	redisReader *r = reader;
	if (r->reply == NULL) {
		r->privdata = privdata;
		return REDIS_OK;
	}
	return REDIS_ERR;
}

/* External libraries wrapping hiredis might need access to the temporary
 * variable while the reply is built up. When the reader contains an
 * object in between receiving some bytes to parse, this object might
 * otherwise be free'd by garbage collection. */
void *redisReplyReaderGetObject(void *reader) {
	redisReader *r = reader;
	return r->reply;
}

void redisReplyReaderFree(void *reader) {
	redisReader *r = reader;
	if (r->error != NULL)
		sdsfree(r->error);
	if (r->reply != NULL && r->fn)
		r->fn->freeObject(r->reply);
	if (r->buf != NULL)
		sdsfree(r->buf);
	free(r);
}

static void redisSetReplyReaderError(redisReader *r, sds err) {
	if (r->reply != NULL)
		r->fn->freeObject(r->reply);

	/* Clear remaining buffer when we see a protocol error. */
	if (r->buf != NULL) {
		sdsfree(r->buf);
		r->buf = sdsempty();
		r->pos = r->len = 0;
	}
	r->ridx = -1;
	r->error = err;
}

char *redisReplyReaderGetError(void *reader) {
	redisReader *r = reader;
	return r->error;
}

void redisReplyReaderFeed(void *reader, const char *buf, size_t len) {
	redisReader *r = reader;

	/* Copy the provided buffer. */
	if (buf != NULL && len >= 1) {
		/* Destroy internal buffer when it is empty and is quite large. */
		if (r->len == 0 && sdsavail(r->buf) > 16 * 1024) {
			sdsfree(r->buf);
			r->buf = sdsempty();
			r->pos = 0;
		}

		r->buf = sdscatlen(r->buf, buf, len);
		r->len = sdslen(r->buf);
	}
}

int redisReplyReaderGetReply(void *reader, void **reply) {
	redisReader *r = reader;
	if (reply != NULL) *reply = NULL;

	/* When the buffer is empty, there will never be a reply. */
	if (r->len == 0)
		return REDIS_OK;

	/* Set first item to process when the stack is empty. */
	if (r->ridx == -1) {
		r->rstack[0].type = -1;
		r->rstack[0].elements = -1;
		r->rstack[0].idx = -1;
		r->rstack[0].obj = NULL;
		r->rstack[0].parent = NULL;
		r->rstack[0].privdata = r->privdata;
		r->ridx = 0;
	}

	/* Process items in reply. */
	while (r->ridx >= 0)
		if (processItem(r) < 0)
			break;

	/* Discard part of the buffer when we've consumed at least 1k, to avoid
	 * doing unnecessary calls to memmove() in sds.c. */
	if (r->pos >= 1024) {
		r->buf = sdsrange(r->buf, r->pos, -1);
		r->pos = 0;
		r->len = sdslen(r->buf);
	}

	/* Emit a reply when there is one. */
	if (r->ridx == -1) {
		void *aux = r->reply;
		r->reply = NULL;

		/* Check if there actually *is* a reply. */
		if (r->error != NULL) {
			return REDIS_ERR;
		}
		else {
			if (reply != NULL) *reply = aux;
		}
	}
	return REDIS_OK;
}

/* Calculate the number of bytes needed to represent an integer as string. */
static int intlen(int i) {
	int len = 0;
	if (i < 0) {
		len++;
		i = -i;
	}
	do {
		len++;
		i /= 10;
	} while (i);
	return len;
}

/* Helper function for redisvFormatCommand(). */
static void addArgument(sds a, char ***argv, int *argc, int *totlen) {
	(*argc)++;
	if ((*argv = (char **)realloc(*argv, sizeof(char*)*(*argc))) == NULL) redisOOM();
	if (totlen) *totlen = *totlen + 1 + intlen(sdslen(a)) + 2 + sdslen(a) + 2;
	(*argv)[(*argc) - 1] = a;
}

int redisvFormatCommand(char **target, const char *format, va_list ap) {
	size_t size;
	const char *arg, *c = format;
	char *cmd = NULL; /* final command */
	int pos; /* position in final command */
	sds current; /* current argument */
	int touched = 0; /* was the current argument touched? */
	char **argv = NULL;
	int argc = 0, j;
	int totlen = 0;

	/* Abort if there is not target to set */
	if (target == NULL)
		return -1;

	/* Build the command string accordingly to protocol */
	current = sdsempty();
	while (*c != '\0') {
		if (*c != '%' || c[1] == '\0') {
			if (*c == ' ') {
				if (touched) {
					addArgument(current, &argv, &argc, &totlen);
					current = sdsempty();
					touched = 0;
				}
			}
			else {
				current = sdscatlen(current, c, 1);
				touched = 1;
			}
		}
		else {
			switch (c[1]) {
			case 's':
				arg = va_arg(ap, char*);
				size = strlen(arg);
				if (size > 0)
					current = sdscatlen(current, arg, size);
				break;
			case 'b':
				arg = va_arg(ap, char*);
				size = va_arg(ap, size_t);
				if (size > 0)
					current = sdscatlen(current, arg, size);
				break;
			case '%':
				current = sdscat(current, "%");
				break;
			default:
				/* Try to detect printf format */
				{
					char _format[16];
					const char *_p = c + 1;
					size_t _l = 0;
					va_list _cpy;

					/* Flags */
					if (*_p != '\0' && *_p == '#') _p++;
					if (*_p != '\0' && *_p == '0') _p++;
					if (*_p != '\0' && *_p == '-') _p++;
					if (*_p != '\0' && *_p == ' ') _p++;
					if (*_p != '\0' && *_p == '+') _p++;

					/* Field width */
					while (*_p != '\0' && isdigit(*_p)) _p++;

					/* Precision */
					if (*_p == '.') {
						_p++;
						while (*_p != '\0' && isdigit(*_p)) _p++;
					}

					/* Modifiers */
					if (*_p != '\0') {
						if (*_p == 'h' || *_p == 'l') {
							/* Allow a single repetition for these modifiers */
							if (_p[0] == _p[1]) _p++;
							_p++;
						}
					}

					/* Conversion specifier */
					if (*_p != '\0' && strchr("diouxXeEfFgGaA", *_p) != NULL) {
						_l = (_p + 1) - c;
						if (_l < sizeof(_format) - 2) {
							memcpy(_format, c, _l);
							_format[_l] = '\0';
							va_copy(_cpy, ap);
							current = sdscatvprintf(current, _format, _cpy);
							va_end(_cpy);

							/* Update current position (note: outer blocks
							 * increment c twice so compensate here) */
							c = _p - 1;
						}
					}

					/* Consume and discard vararg */
#ifdef _WIN32
					va_arg(ap, void*);
#else
					va_arg(ap, void);
#endif
				}
			}
			touched = 1;
			c++;
		}
		c++;
	}

	/* Add the last argument if needed */
	if (touched) {
		addArgument(current, &argv, &argc, &totlen);
	}
	else {
		sdsfree(current);
	}

	/* Add bytes needed to hold multi bulk count */
	totlen += 1 + intlen(argc) + 2;

	/* Build the command at protocol level */
	cmd = (char*)malloc(totlen + 1);
	if (!cmd) redisOOM();
	pos = sprintf(cmd, "*%d\r\n", argc);
	for (j = 0; j < argc; j++) {
#ifdef _WIN32
		pos += sprintf(cmd + pos, "$%llu\r\n", (unsigned long long)sdslen(argv[j]));
#else
		pos += sprintf(cmd + pos, "$%zu\r\n", sdslen(argv[j]));
#endif
		memcpy(cmd + pos, argv[j], sdslen(argv[j]));
		pos += sdslen(argv[j]);
		sdsfree(argv[j]);
		cmd[pos++] = '\r';
		cmd[pos++] = '\n';
	}
	assert(pos == totlen);
	free(argv);
	cmd[totlen] = '\0';
	*target = cmd;
	return totlen;
}

/* Format a command according to the Redis protocol. This function
 * takes a format similar to printf:
 *
 * %s represents a C null terminated string you want to interpolate
 * %b represents a binary safe string
 *
 * When using %b you need to provide both the pointer to the string
 * and the length in bytes. Examples:
 *
 * len = redisFormatCommand(target, "GET %s", mykey);
 * len = redisFormatCommand(target, "SET %s %b", mykey, myval, myvallen);
 */
int redisFormatCommand(char **target, const char *format, ...) {
	va_list ap;
	int len;
	va_start(ap, format);
	len = redisvFormatCommand(target, format, ap);
	va_end(ap);
	return len;
}

/* Format a command according to the Redis protocol. This function takes the
 * number of arguments, an array with arguments and an array with their
 * lengths. If the latter is set to NULL, strlen will be used to compute the
 * argument lengths.
 */
int redisFormatCommandArgv(char **target, int argc, const char **argv, const size_t *argvlen) {
	char *cmd = NULL; /* final command */
	int pos; /* position in final command */
	size_t len;
	int totlen, j;

	/* Calculate number of bytes needed for the command */
	totlen = 1 + intlen(argc) + 2;
	for (j = 0; j < argc; j++) {
		len = argvlen ? argvlen[j] : strlen(argv[j]);
		totlen += 1 + intlen(len) + 2 + len + 2;
	}

	/* Build the command at protocol level */
	cmd = malloc(totlen + 1);
	if (!cmd) redisOOM();
	pos = sprintf(cmd, "*%d\r\n", argc);
	for (j = 0; j < argc; j++) {
		len = argvlen ? argvlen[j] : strlen(argv[j]);
#ifdef _WIN32
		pos += sprintf(cmd + pos, "$%llu\r\n", (unsigned long long)len);
#else
		pos += sprintf(cmd + pos, "$%zu\r\n", len);
#endif
		memcpy(cmd + pos, argv[j], len);
		pos += len;
		cmd[pos++] = '\r';
		cmd[pos++] = '\n';
	}
	assert(pos == totlen);
	cmd[totlen] = '\0';
	*target = cmd;
	return totlen;
}

void __redisSetError(redisContext *c, int type, const sds errstr) {
	c->err = type;
	if (errstr != NULL) {
		c->errstr = errstr;
	}
	else {
		/* Only REDIS_ERR_IO may lack a description! */
		assert(type == REDIS_ERR_IO);
		c->errstr = sdsnew(strerror(errno));
	}
}

static redisContext *redisContextInit(void) {
	redisContext *c = calloc(sizeof(redisContext), 1);
	c->err = 0;
	c->errstr = NULL;
	c->obuf = sdsempty();
	c->fn = &defaultFunctions;
	c->reader = NULL;
	return c;
}

void redisFree(redisContext *c) {
	if (c->fd > 0)
#ifdef _WIN32
		closesocket(c->fd);
#else
		close(c->fd);
#endif
	if (c->errstr != NULL)
		sdsfree(c->errstr);
	if (c->obuf != NULL)
		sdsfree(c->obuf);
	if (c->reader != NULL)
		redisReplyReaderFree(c->reader);
	free(c);
}

/* Connect to a Redis instance. On error the field error in the returned
 * context will be set to the return value of the error function.
 * When no set of reply functions is given, the default set will be used. */
redisContext *redisConnect(const char *ip, int port) {
	redisContext *c = redisContextInit();
	c->flags |= REDIS_BLOCK;
	redisContextConnectTcp(c, ip, port, NULL);
	return c;
}

redisContext *redisConnectWithTimeout(const char *ip, int port, struct timeval tv) {
	redisContext *c = redisContextInit();
	c->flags |= REDIS_BLOCK;
	redisContextConnectTcp(c, ip, port, &tv);
	return c;
}

redisContext *redisConnectNonBlock(const char *ip, int port) {
	redisContext *c = redisContextInit();
	c->flags &= ~REDIS_BLOCK;
	redisContextConnectTcp(c, ip, port, NULL);
	return c;
}

redisContext *redisConnectUnix(const char *path) {
	redisContext *c = redisContextInit();
	c->flags |= REDIS_BLOCK;
	redisContextConnectUnix(c, path, NULL);
	return c;
}

redisContext *redisConnectUnixWithTimeout(const char *path, struct timeval tv) {
	redisContext *c = redisContextInit();
	c->flags |= REDIS_BLOCK;
	redisContextConnectUnix(c, path, &tv);
	return c;
}

redisContext *redisConnectUnixNonBlock(const char *path) {
	redisContext *c = redisContextInit();
	c->flags &= ~REDIS_BLOCK;
	redisContextConnectUnix(c, path, NULL);
	return c;
}

/* initializers if caller handles connection */
redisContext *redisConnected() {
	redisContext *c = redisContextInit();
	c->fd = -1;
	c->flags |= REDIS_BLOCK;
	return c;
}

redisContext *redisConnectedNonBlock() {
	redisContext *c = redisContextInit();
	c->fd = -1;
	c->flags &= ~REDIS_BLOCK;
	return c;
}

/* Set read/write timeout on a blocking socket. */
int redisSetTimeout(redisContext *c, struct timeval tv) {
	if (c->flags & REDIS_BLOCK)
		return redisContextSetTimeout(c, tv);
	return REDIS_ERR;
}

/* Set the replyObjectFunctions to use. Returns REDIS_ERR when the reader
 * was already initialized and the function set could not be re-set.
 * Return REDIS_OK when they could be set. */
int redisSetReplyObjectFunctions(redisContext *c, redisReplyObjectFunctions *fn) {
	if (c->reader != NULL)
		return REDIS_ERR;
	c->fn = fn;
	return REDIS_OK;
}

/* Helper function to lazily create a reply reader. */
static void __redisCreateReplyReader(redisContext *c) {
	if (c->reader == NULL) {
		c->reader = redisReplyReaderCreate();
		assert(redisReplyReaderSetReplyObjectFunctions(c->reader, c->fn) == REDIS_OK);
	}
}

/* Use this function to handle a read event on the descriptor. It will try
 * and read some bytes from the socket and feed them to the reply parser.
 *
 * After this function is called, you may use redisContextReadReply to
 * see if there is a reply available. */
int redisBufferRead(redisContext *c) {
	char buf[2048];
#ifdef _WIN32
	int nread = recv((SOCKET)c->fd, buf, sizeof(buf), 0);
	if (nread == -1) {
		errno = WSAGetLastError();
		if ((errno == ENOENT) || (errno == WSAEWOULDBLOCK))
			errno = EAGAIN;
	}
#else
	int nread = read(c->fd, buf, sizeof(buf));
#endif
	if (nread == -1) {
		if (errno == EAGAIN && !(c->flags & REDIS_BLOCK)) {
			/* Try again later */
		}
		else {
			__redisSetError(c, REDIS_ERR_IO, NULL);
			return REDIS_ERR;
		}
	}
	else if (nread == 0) {
		__redisSetError(c, REDIS_ERR_EOF,
			sdsnew("Server closed the connection"));
		return REDIS_ERR;
	}
	else {
		__redisCreateReplyReader(c);
		redisReplyReaderFeed(c->reader, buf, nread);
	}
	return REDIS_OK;
}

/* Use this function if the caller has already read the data. It will
 * feed bytes to the reply parser.
 *
 * After this function is called, you may use redisContextReadReply to
 * see if there is a reply available. */
int redisBufferReadDone(redisContext *c, char *buf, int nread) {
	if (nread == 0) {
		__redisSetError(c, REDIS_ERR_EOF,
			sdsnew("Server closed the connection"));
		return REDIS_ERR;
	}
	else {
		__redisCreateReplyReader(c);
		redisReplyReaderFeed(c->reader, buf, nread);
	}
	return REDIS_OK;
}

/* Write the output buffer to the socket.
 *
 * Returns REDIS_OK when the buffer is empty, or (a part of) the buffer was
 * succesfully written to the socket. When the buffer is empty after the
 * write operation, "wdone" is set to 1 (if given).
 *
 * Returns REDIS_ERR if an error occured trying to write and sets
 * c->error to hold the appropriate error string.
 */
int redisBufferWrite(redisContext *c, int *done) {
	int nwritten;
	if (sdslen(c->obuf) > 0) {
#ifdef _WIN32
		nwritten = send((SOCKET)c->fd, c->obuf, sdslen(c->obuf), 0);
		if (nwritten == -1) {
			errno = WSAGetLastError();
			if ((errno == ENOENT) || (errno == WSAEWOULDBLOCK))
				errno = EAGAIN;
		}
#else
		nwritten = write(c->fd, c->obuf, sdslen(c->obuf));
#endif
		if (nwritten == -1) {
			if (errno == EAGAIN && !(c->flags & REDIS_BLOCK)) {
				/* Try again later */
			}
			else {
				__redisSetError(c, REDIS_ERR_IO, NULL);
				return REDIS_ERR;
			}
		}
		else if (nwritten > 0) {
			if (nwritten == (signed)sdslen(c->obuf)) {
				sdsfree(c->obuf);
				c->obuf = sdsempty();
			}
			else {
				c->obuf = sdsrange(c->obuf, nwritten, -1);
			}
		}
	}
	if (done != NULL) *done = (sdslen(c->obuf) == 0);
	return REDIS_OK;
}

/* Internal helper function to try and get a reply from the reader,
 * or set an error in the context otherwise. */
int redisGetReplyFromReader(redisContext *c, void **reply) {
	__redisCreateReplyReader(c);
	if (redisReplyReaderGetReply(c->reader, reply) == REDIS_ERR) {
		__redisSetError(c, REDIS_ERR_PROTOCOL,
			sdsnew(((redisReader*)c->reader)->error));
		return REDIS_ERR;
	}
	return REDIS_OK;
}

int redisGetReply(redisContext *c, void **reply) {
	int wdone = 0;
	void *aux = NULL;

	/* Try to read pending replies */
	if (redisGetReplyFromReader(c, &aux) == REDIS_ERR)
		return REDIS_ERR;

	/* For the blocking context, flush output buffer and read reply */
	if (aux == NULL && c->flags & REDIS_BLOCK) {
		/* Write until done */
		do {
			if (redisBufferWrite(c, &wdone) == REDIS_ERR)
				return REDIS_ERR;
		} while (!wdone);

		/* Read until there is a reply */
		do {
			if (redisBufferRead(c) == REDIS_ERR)
				return REDIS_ERR;
			if (redisGetReplyFromReader(c, &aux) == REDIS_ERR)
				return REDIS_ERR;
		} while (aux == NULL);
	}

	/* Set reply object */
	if (reply != NULL) *reply = aux;
	return REDIS_OK;
}


/* Helper function for the redisAppendCommand* family of functions.
 *
 * Write a formatted command to the output buffer. When this family
 * is used, you need to call redisGetReply yourself to retrieve
 * the reply (or replies in pub/sub).
 */
void __redisAppendCommand(redisContext *c, char *cmd, size_t len) {
	c->obuf = sdscatlen(c->obuf, cmd, len);
}

void redisvAppendCommand(redisContext *c, const char *format, va_list ap) {
	char *cmd;
	int len;
	len = redisvFormatCommand(&cmd, format, ap);
	__redisAppendCommand(c, cmd, len);
	free(cmd);
}

void redisAppendCommand(redisContext *c, const char *format, ...) {
	va_list ap;
	va_start(ap, format);
	redisvAppendCommand(c, format, ap);
	va_end(ap);
}

void redisAppendCommandArgv(redisContext *c, int argc, const char **argv, const size_t *argvlen) {
	char *cmd;
	int len;
	len = redisFormatCommandArgv(&cmd, argc, argv, argvlen);
	__redisAppendCommand(c, cmd, len);
	free(cmd);
}

/* Helper function for the redisCommand* family of functions.
 *
 * Write a formatted command to the output buffer. If the given context is
 * blocking, immediately read the reply into the "reply" pointer. When the
 * context is non-blocking, the "reply" pointer will not be used and the
 * command is simply appended to the write buffer.
 *
 * Returns the reply when a reply was succesfully retrieved. Returns NULL
 * otherwise. When NULL is returned in a blocking context, the error field
 * in the context will be set.
 */
static void *__redisCommand(redisContext *c, char *cmd, size_t len) {
	void *aux = NULL;
	__redisAppendCommand(c, cmd, len);

	if (c->flags & REDIS_BLOCK) {
		if (redisGetReply(c, &aux) == REDIS_OK)
			return aux;
		return NULL;
	}
	return NULL;
}

void *redisvCommand(redisContext *c, const char *format, va_list ap) {
	char *cmd;
	int len;
	void *reply = NULL;
	len = redisvFormatCommand(&cmd, format, ap);
	reply = __redisCommand(c, cmd, len);
	free(cmd);
	return reply;
}

void *redisCommand(redisContext *c, const char *format, ...) {
	va_list ap;
	void *reply = NULL;
	va_start(ap, format);
	reply = redisvCommand(c, format, ap);
	va_end(ap);
	return reply;
}

void *redisCommandArgv(redisContext *c, int argc, const char **argv, const size_t *argvlen) {
	char *cmd;
	int len;
	void *reply = NULL;
	len = redisFormatCommandArgv(&cmd, argc, argv, argvlen);
	reply = __redisCommand(c, cmd, len);
	free(cmd);
	return reply;
}
